IB/cma: Fix net_dev reference leak with failed requests

Hello Haggai Eran,

The patch be688195bd08: "IB/cma: Fix net_dev reference leak with failed requests" from Aug 27, 2015, leads to the following static checker warning:

	drivers/infiniband/core/cma.c:1306 cma_id_from_event()
	error: potential NULL dereference '*net_dev'.

drivers/infiniband/core/cma.c
1279 static struct rdma_id_private *cma_id_from_event(struct ib_cm_id *cm_id,
1280 struct ib_cm_event *ib_event,
1281 struct net_device **net_dev)
1282 {

  1283          struct cma_req_info req;
  1284          struct rdma_bind_list *bind_list;
  1285          struct rdma_id_private *id_priv;
  1286          int err;

1287
1288 err = cma_save_req_info(ib_event, &req);
1289 if (err)
1290 return ERR_PTR(err);
1291
1292 *net_dev = cma_get_net_dev(ib_event, &req);
1293 if (IS_ERR(*net_dev)) {
1294 if (PTR_ERR(*net_dev) == -EAFNOSUPPORT) {
1295 /* Assuming the protocol is AF_IB */
1296 *net_dev = NULL;

Set to NULL here.

  1297                  } else {
  1298                          return ERR_CAST(*net_dev);
  1299                  }
  1300          }
  1301  
  1302          bind_list = cma_ps_find(rdma_ps_from_service_id(req.service_id),
  1303                                  cma_port_from_service_id(req.service_id));
  1304          id_priv = cma_find_listener(bind_list, cm_id, ib_event, &req, *net_dev);
  1305          if (IS_ERR(id_priv)) {
  1306                  dev_put(*net_dev);

Dereferenced inside function call. This warning is from a work in progress Smatch check (unpublished).

  1307                  *net_dev = NULL;
  1308          }
  1309  
  1310          return id_priv;
  1311  }

regards,
dan carpenter
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